Maternal ethnic ancestry and adverse perinatal outcomes in New York City

Objective We sought to examine the association between narrowly defined subsets of maternal ethnicity and birth outcomes. Study Design We analyzed 1995–2003 New York City birth certificates linked to hospital discharge data for 949,210 singleton births to examine the multivariable associations between maternal ethnicity and preterm birth, subsets of spontaneous and medically indicated preterm birth, term small for gestational age, and term birthweight. Results Compared with non-Hispanic whites, Puerto Ricans had an elevated odds ratio (1.9; 95% confidence interval, 1.9–2.0) for delivering at 32–36 weeks (adjusted for nativity, maternal age, parity, education, tobacco use, prepregnancy weight, and birth year). We found an excess of adverse outcomes among most Latino groups. Outcomes also varied within regions, with North African infants nearly 100 g (adjusted) heavier than sub-Saharan African infants. Conclusion The considerable heterogeneity in risk of adverse perinatal outcomes is obscured in broad categorizations of maternal race/ethnicity and may help to formulate etiologic hypotheses.